Haley's real life lesson

I recently have scheduled playdates with other moms and kids who are the same age as Haley. During a few hours of play time, we hear the same phrases like "it's mine!" and "no!" Everyone of them cries at a different time because they are upset that they can't get what they want spontaneously. The lesson to share and take turn is so new and tough for them. It is hard on both moms and our kids. We as mom has to be sympathetic to their feelings, yet need to be firm to stick to the rules when playing with others. Haley will repeat the rules to me before and after each playdates, but she definitely need more practice in order to put the rules in her life.